TW202247993A - Wiring board and method for manufacturing wiring board - Google Patents

Abstract

A wiring board, comprising: wiring patterns that are buried with the wiring board, in which at least one of thickness regions to a thickness position of 7 [mu]m toward a direction away from the wiring patterns with each of one surface and the other surface of the wiring pattern in a thickness direction as a reference has an elastic modulus at 240 DEG C equal to or greater than 300 MPa, and a dielectric loss tangent is equal to or less than 0.006.

Description

Wiring board and manufacturing method of wiring board

The disclosure relates to a wiring substrate and a method for manufacturing the wiring substrate.

In recent years, the frequency used in communication equipment tends to become higher. In order to suppress transmission loss in a high frequency band, it is required to lower the relative permittivity and dielectric loss tangent of insulating materials used for circuit boards.

For example, Patent Document 1 describes a circuit board having a laminated structure. The laminated structure has a plurality of thermoplastic liquid crystal polymer films and at least one conductive layer. At least a part of the laminated structure includes a conductor layer processed with a circuit between two sheets. Structure between layers of thermoplastic liquid crystal polymer film.

[Patent Document 1] International Publication No. 2016/072361

The problem to be solved by one embodiment of the present invention is to provide a wiring board and a method of manufacturing the wiring board which are excellent in wiring followability and suppress wiring deformation.

Mechanisms for solving the above-mentioned problems include the following aspects. <1> A wiring board in which a wiring pattern is buried, with at least one of the thickness regions facing away from the wiring pattern to a thickness position of 7 μm based on each of one surface and the other surface in the thickness direction of the wiring pattern One has an elastic modulus at 240° C. of 300 MPa or more and a dielectric loss tangent of 0.006 or less. <2> A wiring board in which a wiring pattern is embedded, with one surface and the other surface in the thickness direction of the wiring pattern as a reference, facing a direction away from the wiring pattern up to 40% of the thickness of the wiring pattern At least one of the thickness regions up to the thickness position has an elastic modulus at 240° C. of 300 MPa or more and a dielectric loss tangent of 0.006 or less. <3> The wiring board as described in <1> or <2>, wherein the thickness of the wiring pattern is 5 μm to 40 μm. <4> The wiring board according to any one of <1> to <3>, which includes a base material, a wiring pattern disposed on at least one surface of the base material, and a wiring pattern disposed between the wiring patterns. For the upper resin layer, the dielectric loss tangent of the substrate is 0.006 or less. <5> The wiring board as described in <4>, wherein the base material contains a liquid crystal polymer. <6> The wiring board according to <5>, wherein the liquid crystal polymer has a constituent unit represented by any one of formula (1) to formula (3). Formula (1) -O-Ar ¹ -CO- Formula (2) -CO-Ar ² -CO- Formula (3) -X-Ar ³ -Y- In formula (1) to formula (3), Ar ¹ represents phenylene, naphthylene or biphenylene, Ar ² and Ar ³ independently represent phenylene, naphthylene, biphenylene or a group represented by the following formula (4), X and Y Each independently represents an oxygen atom or an imine group, and at least one of the hydrogen atoms in Ar ¹ to Ar ³ can be independently replaced by a halogen atom, an alkyl group or an aryl group, the formula (4)-Ar ⁴ -Z-Ar ⁵ - In the formula (4), Ar ⁴ and Ar ⁵ independently represent a phenylene group or a naphthylene group, and Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylene group. <7> The wiring board according to <5> or <6>, wherein the elastic modulus at 240° C. of the resin layer is 0.1 MPa or less. <8> A method of manufacturing a wiring board comprising: a step of overlapping a resin base material on a wiring pattern of a wiring pattern base material; and performing the steps of overlapping the wiring pattern base material and the resin base material In the step of heating to obtain a wiring board, the elastic modulus at the heating temperature when the substrates with wiring patterns are heated in a stacked state is 300 MPa or more, and the dielectric loss tangent of the wiring board is 0.006 or less. <9> The method for producing a wiring board according to <8>, wherein the resin base material contains a thermoplastic polymer, and the heating temperature is lower than the melting point of the thermoplastic polymer when heating in a stacked state. <10> The method for producing a wiring board as described in <9>, wherein the resin base material further contains a compound having a melting point lower than that of the thermoplastic polymer, and the heating temperature is higher than that of the compound when heating in a stacked state. temperature of the melting point. <11> The method for producing a wiring board according to <10>, wherein the compound has a dielectric loss tangent of 0.01 or less. <12> The method for producing a wiring board according to any one of <8> to <11>, wherein the resin base material has an elastic modulus of 0.1 MPa or less at the heating temperature when the resin base material is heated in a stacked state. [Invention effect]

According to one embodiment of the present invention, there are provided a wiring board having excellent wiring followability and suppressing wiring deformation, and a method of manufacturing the wiring board.

Hereinafter, the contents of the present disclosure will be described in detail. The description of the constituent requirements described below may be based on representative embodiments of the present disclosure, but the present disclosure is not limited to these embodiments. In addition, in this specification, "-" which shows a numerical range is used in the meaning which includes the numerical value described before and after it as a lower limit and an upper limit. In the numerical ranges recorded step by step in this disclosure, the upper limit or lower limit described in one numerical range can be replaced with the upper limit or lower limit in other numerical ranges recorded stepwise. Moreover, in the numerical range described in this indication, the upper limit or the lower limit of the numerical range can be replaced with the value shown in an Example. In addition, in the expression of the group (atomic group) in this specification, the expression which does not describe substitution and unsubstituted includes the thing which does not have a substituent, and also includes the thing which has a substituent. For example, "alkyl" includes not only an unsubstituted alkyl group (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group). In this specification, "(meth)acrylic" refers to the term used in the concept including both acrylic and methacrylic, and "(meth)acryl" refers to a term used to include both acryl and methacryl. Acryloyl group is the term for both concepts. In addition, the term "step" in this specification is not only an independent step, but even when it cannot be clearly distinguished from other steps, as long as the intended purpose of the step is achieved, it is included in this term. Moreover, in this indication, the definition of "mass %" is the same as the definition of "weight%", and the definition of "mass part" is the same as the definition of "weight part". In addition, in this indication, the combination of 2 or more preferable aspects is a more preferable aspect. In addition, unless otherwise specified, the weight average molecular weight (Mw) and number average molecular weight (Mn) in this disclosure are obtained by gel permeation chromatography using a column of TSKgel SuperHM-H (product name manufactured by TOSOH Corporation). (GPC) analysis device and detection by the solvent PFP (pentafluorophenol) / chloroform = 1/2 (mass ratio), differential refractometer, and the molecular weight converted using polystyrene as a standard substance. In the present disclosure, "wiring followability" refers to the property that a layer in contact with a wiring pattern (specifically, a resin layer or a base material) follows the wiring pattern and is easily deformed. Specifically, it refers to the property that a gap hardly occurs between a resin layer or a base material and a wiring pattern.

[Wiring board] In the first aspect of the wiring board of the present disclosure, the wiring pattern is embedded, and the wiring pattern is buried in a direction away from the wiring pattern to a thickness position of 7 μm on the basis of each of the one surface and the other surface in the thickness direction of the wiring pattern. At least one of the thickness regions has an elastic modulus at 240° C. of 300 MPa or more, and a dielectric loss tangent of 0.006 or less. In the second aspect of the wiring board of the present disclosure, the wiring pattern is buried, and the wiring pattern is oriented in a direction away from the wiring pattern to an area corresponding to the wiring pattern on the basis of each of one surface and the other surface in the thickness direction of the wiring pattern. At least one of the thickness regions up to the thickness position of 40% of the thickness has an elastic modulus at 240° C. of 300 MPa or more and a dielectric loss tangent of 0.006 or less.

As a result of earnest research, the present inventors have found that by adopting the above-mentioned structure, it is possible to provide a wiring board that is excellent in wiring followability and suppresses wiring deformation. Although the detailed mechanism for obtaining the above effects is not clear, it is presumed as follows. In the wiring board of the present disclosure, based on each of one surface and the other surface in the thickness direction of the wiring pattern, at least one of the thickness regions up to a specific thickness position has an elastic modulus at 240°C of Since it is 300 MPa or more, it is considered that the stress on the wiring is reduced, the deformation of the wiring is suppressed, and the wiring followability is excellent. The above specific thickness position is a thickness position of 7 μm in the direction away from the wiring pattern or a thickness position corresponding to 40% of the thickness of the wiring pattern in the direction away from the wiring pattern.

In contrast, Patent Document 1 does not pay attention to the elastic modulus at 240° C. in the thickness region up to a specific thickness position based on each of the one surface and the other surface in the thickness direction of the wiring pattern.

Hereinafter, the wiring board of this disclosure is demonstrated in detail.

The wiring board of the present disclosure has a wiring pattern, and the wiring pattern is buried. The wiring pattern can be embedded in the wiring board by the following method, for example. First, a metal layer is formed on a substrate, and the metal layer is etched in a pattern. Thereby, the base material which arrange|positioned the wiring pattern on at least one surface (henceforth also referred to as "the base material with wiring pattern") was obtained. Next, the base material with a wiring pattern and another base material are superimposed so that the wiring pattern in the base material with a wiring pattern becomes inside. After overlapping the base material with the wiring pattern and other base materials, lamination or heat welding can be performed. Thereby, the wiring board in which the wiring pattern was embedded was obtained.

In the present disclosure, "the wiring pattern is buried" means that at least a part of the wiring pattern exists inside the wiring board.

The material of the wiring pattern is not particularly limited, and metal is preferred, and silver or copper is more preferred.

In the first aspect of the wiring board of the present disclosure, at least part of the thickness region facing away from the wiring pattern to a thickness position of 7 μm is based on each of one surface and the other surface in the thickness direction of the wiring pattern. One has an elastic modulus of 300 MPa or more at 240°C. In the second aspect of the wiring board of the present disclosure, on the basis of each of one surface and the other surface in the thickness direction of the wiring pattern, the direction away from the wiring pattern corresponds to 40% of the thickness of the wiring pattern. At least one of the thickness regions up to the thickness position has an elastic modulus at 240° C. of 300 MPa or more. Since the elastic modulus at 240° C. is 300 MPa or more, wiring deformation is suppressed. Hereinafter, both the thickness position of 7 μm in the direction away from the wiring pattern and the thickness position corresponding to 40% of the thickness of the wiring pattern in the direction away from the wiring pattern are referred to as “specific thickness positions”.

In the wiring board of the present disclosure, as long as the wiring pattern is embedded, the material of the region other than the wiring pattern is not particularly limited. Also, at least one of the thickness regions up to a specific thickness position may have an elastic modulus of 300 MPa or more at 240° C. based on each of the one surface and the other surface in the thickness direction of the wiring pattern. The material is not particularly limited.

The thickness region up to a specific thickness position refers to, for example, P11 and P12 in FIG. 1 based on each of one surface and the other surface in the thickness direction of the wiring pattern (starting point). In addition, in FIG. 2 , two wiring patterns are embedded in the thickness direction of the wiring board, and the above-mentioned thickness regions refer to P21 and P22 and P31 and P32. In wiring board 100 in FIG. 1 , at least one of thickness regions P11 and P12 has an elastic modulus at 240° C. of 300 MPa or more. In the wiring board 200 in FIG. 2 , at least one of the thickness regions P21 and P22 has an elastic modulus at 240° C. of 300 MPa or more, and at least one of the thickness regions P31 and P32 has an elastic modulus at 240° C. of 300 MPa. above.

In the present disclosure, the elastic modulus refers to the indentation elastic modulus (E _IT ). The modulus of elasticity at 240°C is the modulus of elasticity measured in an environment of 240°C.

The elastic modulus of the thickness region toward a direction away from the wiring pattern to a thickness position of 7 μm was measured by the following method.

First, cut the cross-section of the wiring board with a microtome, observe the image near the wiring with an optical microscope, and use one side and the other side in the thickness direction of the wiring pattern as a reference to specify the direction away from the wiring pattern. The thickness region in the direction to the thickness position of 7 μm. Next, using the nanoindentation method, the elastic modulus in the above-mentioned specific region was measured as the indentation elastic modulus. The indentation modulus of elasticity is measured using a micro-hardness meter, for example, by using a micro-hardness meter (product name "DUH-W201", manufactured by Shimadzu Corporation) with a Vickers indenter at a load of 0.28 mN/sec. Speed Apply a load to the above-mentioned specific area, keep the maximum load of 10mN for 10 seconds, and then unload at a load speed of 0.28mN/second. In addition, the elastic modulus of the thickness region up to the thickness position corresponding to 40% of the thickness of the wiring pattern in the direction away from the wiring pattern is used instead of the thickness region of 7 μm in the direction away from the wiring pattern, and the corresponding wiring pattern is specified. The thickness region up to the thickness position of 40% of the thickness of the pattern was measured by the same method as above except that.

From the viewpoint of improving wiring followability and further suppressing wiring deformation, at least one of the thickness regions up to a specific thickness position is at 240°C based on each of one surface and the other surface in the thickness direction of the wiring pattern. The lower elastic modulus is preferably 300 MPa or more, more preferably 400 MPa or more. The upper limit of the elastic modulus is not particularly limited, and is, for example, 9000 MPa.

The thickness of the wiring pattern is not particularly limited, but is preferably 5 μm to 40 μm, more preferably 5 μm to 35 μm.

The thickness of the wiring pattern was measured by cutting the wiring board with a microtome and observing it with an optical microscope.

The dielectric loss tangent of the wiring board of the present disclosure is 0.006 or less, preferably more than 0 and 0.003 or less. Since the dielectric loss tangent is 0.006 or less, transmission loss can be reduced.

In the present disclosure, dielectric loss tangent is measured using the following method. It was carried out by the resonance perturbation method at a frequency of 28 GHz. Specifically, a split cylinder resonator (manufactured by KANTO Electronic Application and Development Inc.) was connected to a network analyzer (manufactured by Keysight Technologies "N5230A"), and a test piece (width: 25mm x length: 50mm, 24°C. 50% • 24-hour humidity control) was inserted into the cavity resonator, and the dielectric loss tangent was measured from the change of the resonant frequency before and after insertion and using the analysis software made by KANTO Electronic Application and Development Inc. In addition, when a wiring board consists of several layers, the dielectric loss tangent of a wiring board is computed from the dielectric loss tangent and thickness of each layer using the following formula. Dielectric loss tangent of the wiring board = Σ (dielectric loss tangent of each layer × thickness of each layer / total thickness of each layer)

The wiring board of the present disclosure preferably includes a base material, a wiring pattern disposed on at least one surface of the base material, and a resin layer disposed between the wiring patterns and on the wiring pattern.

FIG. 1 is a schematic cross-sectional view showing an example of a wiring board of the present disclosure. A wiring board 100 shown in FIG. 1 includes a base material 10 , wiring patterns 20 arranged on one surface of the base material 10 , and a resin layer 30 arranged between the wiring patterns 20 and on the wiring patterns 20 .

FIG. 2 is a schematic cross-sectional view showing another example of the wiring board of the present disclosure. The wiring substrate 200 shown in FIG. 2 includes a base material 40, wiring patterns 50 and 70 arranged on both surfaces of the base material 40, a resin layer 60 arranged between the wiring patterns 50 and on the wiring pattern 50, and a wiring pattern arranged on the wiring pattern 50. The resin layer 80 between the patterns 70 and on the wiring pattern 70 .

When the substrate 40 is a uniform single layer, the elastic modulus at 240° C. is the same in the thickness region P22 and the thickness region P31 . Moreover, when the resin layer 60 and the resin layer 80 are layers formed by the same method, the elastic modulus at 240 degreeC of thickness area|region P21 and thickness area|region P32 is the same. Therefore, when the base material 40 is a uniform single layer, what is necessary is just to measure the elastic modulus at 240 degreeC about either of thickness area|region P22 and thickness area|region P31. Moreover, when the resin layer 60 and the resin layer 80 are layers formed by the same method, what is necessary is just to measure the elastic modulus in 240 degreeC about either of thickness area|region P21 and thickness area|region P32.

-Substrate- It is preferable that a wiring board has a base material. The material of the substrate is not particularly limited, and preferably contains resin.

The dielectric loss tangent of the base material is preferably 0.006 or less, more preferably more than 0 and 0.003 or less.

Examples of the resin contained in the substrate include liquid crystal polymers, fluorine-based polymers, polymers of compounds having cyclic aliphatic hydrocarbon groups and ethylenically unsaturated bond groups, polyetheretherketone, poly Olefin, polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfide, polyphenylene ether and its modified substances, polyether imide and other thermoplastic polymers; epoxypropylene methacrylate Elastomers such as copolymers of ester and polyethylene; thermosetting polymers such as phenolic resins, epoxy resins, polyimide resins, and cyanate resins.

Among them, it is preferable that the base material contains a liquid crystal polymer from the viewpoint of dielectric loss tangent.

The liquid crystal polymer may be a thermotropic liquid crystal polymer exhibiting liquid crystallinity in a molten state, or a lyotropic liquid crystal polymer exhibiting liquid crystallinity in a solution state. Also, in the case of thermotropic liquid crystals, those that melt at a temperature of 450° C. or lower are preferable.

Examples of liquid crystal polymers include liquid crystal polyesters, liquid crystal polyesteramides in which amide bonds are introduced into liquid crystal polyesters, liquid crystal polyester ethers in which ether bonds are introduced into liquid crystal polyesters, and liquid crystal polyesters in which carbonic acid is introduced. Ester-bonded liquid crystal polyester carbonate.

Also, from the viewpoint of liquid crystallinity, the liquid crystal polymer is preferably a polymer having an aromatic ring, more preferably an aromatic polyester or an aromatic polyester amide, and even more preferably an aromatic polyester amide.

In addition, the liquid crystal polymer may be a polymer in which an isocyanate-derived bond such as an imide bond, a carbodiimide bond, or an isocyanurate bond is introduced into an aromatic polyester or an aromatic polyester amide.

Also, the liquid crystal polymer is preferably a wholly aromatic liquid crystal polymer obtained by using only aromatic compounds as raw material monomers.

As a liquid crystal polymer, the following are mentioned, for example. 1) At least one compound selected from the group consisting of (i) aromatic hydroxycarboxylic acid, (ii) aromatic dicarboxylic acid and (iii) aromatic diol, aromatic hydroxylamine and aromatic diamine polycondensed. 2) Polycondensation of multiple aromatic hydroxycarboxylic acids. 3) Polycondensation of (i) aromatic dicarboxylic acid and (ii) at least one compound selected from the group consisting of aromatic diol, aromatic hydroxylamine and aromatic diamine. 4) Polycondensation of (i) polyester such as polyethylene terephthalate and (ii) aromatic hydroxycarboxylic acid. Here, aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic hydroxylamines, and aromatic diamines may be replaced by partially or entirely derivatives capable of polycondensation, respectively.

Examples of polymerizable derivatives of compounds having a carboxyl group such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids include those obtained by converting a carboxyl group to an alkoxycarbonyl group or an aryloxycarbonyl group (ester), Those obtained by converting a carboxyl group into a haloformyl group (acid halide) and those obtained by converting a carboxyl group into an acyloxycarbonyl group (acid anhydride).

Examples of polymerizable derivatives of compounds having hydroxyl groups such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxylamines include those obtained by acylating the hydroxyl group to convert it into an acyloxy group (acyloxy group). compounds).

As an example of the polymerizable derivative of the compound which has an amine group, such as aromatic hydroxylamine and an aromatic diamine, the thing which converted an amine group into an amide group by acylation (acyl compound) is mentioned.

From the viewpoint of liquid crystallinity, the liquid crystal polymer has a structural unit represented by any one of the following formulas (1) to (3) (hereinafter, the structural unit represented by the formula (1) may be referred to as a unit ( 1) etc.) is preferred, it is more preferable to have a structural unit represented by the following formula (1), to have a structural unit represented by the following formula (1), a structural unit represented by the following formula (2) and A structural unit represented by the following formula (3) is particularly preferable. Formula (1) -O-Ar ¹ -CO- Formula (2) -CO-Ar ² -CO- Formula (3) -X-Ar ³ -Y- In formula (1) to formula (3), Ar ¹ represents phenylene, naphthylene or biphenylene, Ar ² and Ar ³ independently represent phenylene, naphthylene, biphenylene or a group represented by the following formula (4), X and Y Each independently represents an oxygen atom or an imine group, and at least one of the hydrogen atoms in Ar ¹ to Ar ³ can be independently replaced by a halogen atom, an alkyl group or an aryl group, the formula (4)-Ar ⁴ -Z-Ar ⁵ - In the formula (4), Ar ⁴ and Ar ⁵ independently represent a phenylene group or a naphthylene group, and Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylene group.

As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned. Examples of the above-mentioned alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, secondary butyl, tertiary butyl, n-hexyl, 2-ethylhexyl , n-octyl and n-decyl, preferably having 1-10 carbon atoms. Examples of the aryl group include phenyl, o-tolyl, m-tolyl, p-tolyl, 1-naphthyl and 2-naphthyl, and the carbon number is preferably 6-20. When the aforementioned hydrogen atoms are replaced by these groups, the number is preferably 2 or less, more preferably 1, for each of the aforementioned groups represented by Ar ¹ , Ar ² or Ar ³ .

Examples of the above-mentioned alkylene groups include methylene, 1,1-ethanediyl, 1-methyl-1,1-ethanediyl, 1,1-butanediyl and 2-ethyl-1 , 1-hexanediyl group, preferably having 1-10 carbon atoms.

The unit (1) is a structural unit derived from an aromatic hydroxycarboxylic acid. As unit (1), Ar ¹ is p-phenylene (derived from the constituent unit of p-hydroxybenzoic acid) and Ar ¹ is 2,6-naphthyl (derived from the constituent unit of 6-hydroxy-2-naphthoic acid) unit) or 4,4'-biphenylene (constituent unit derived from 4'-hydroxy-4-biphenylcarboxylic acid) is preferred.

The unit (2) is a structural unit derived from an aromatic dicarboxylic acid. As unit (2), Ar ² is p-phenylene (derived from the constituent unit of terephthalic acid), Ar ² is meta-phenylene (derived from the constituent unit of isophthalic acid), Ar ² is 2 , 6-naphthyl (derived from the constituent unit of 2,6-naphthalene dicarboxylic acid) or Ar ² is diphenyl ether-4,4'-diyl (derived from diphenyl ether-4,4 '-the structural unit of dicarboxylic acid) is preferable.

The unit (3) is a structural unit derived from an aromatic diol, an aromatic hydroxylamine, or an aromatic diamine. As unit (3), Ar ³ is a p-phenylene group (derived from the constituent units of hydroquinone, p-aminophenol or p-phenylenediamine), and Ar ³ is a meta-phenylene group (derived from m-phenylene diamine). formic acid) or Ar ³ is 4,4'-biphenylene (derived from 4,4'-dihydroxybiphenyl, 4-amino-4'-hydroxybiphenyl or 4,4'-diphenylene A constituent unit of aminobiphenyl) is preferred.

The content of the unit (1) relative to the total amount of the total structural units (by dividing the mass of each structural unit constituting the liquid crystal polymer by the formula weight of each unit, the substance equivalent amount (mole) of each unit is obtained , the total value of these; the same below) is preferably 30 mole % or more, more preferably 30 mole % to 80 mole %, further preferably 30 mole % to 60 mole %, especially preferably It is 30 mol % to 40 mol %. The content of the unit (2) is preferably at most 35 mol %, more preferably 10 mol % to 35 mol %, further preferably 20 mol % to 35 mol %, relative to the total amount of the total constituent units, Most preferably, it is 30 mol % to 35 mol %. The content of the unit (3) is preferably 35 mol % or less, more preferably 10 mol % to 35 mol %, further preferably 20 mol % to 35 mol %, relative to the total amount of the total constituent units, Most preferably, it is 30 mol % to 35 mol %. The higher the content of the unit (1), the easier it is to improve heat resistance, strength, and rigidity, but if it is too large, the solubility in solvents tends to decrease.

The ratio of the content of the unit (2) to the content of the unit (3) is represented by [the content of the unit (2)]/[the content of the unit (3)] (mole/mole), preferably 0.9/1～1 /0.9, more preferably 0.95/1 to 1/0.95, still more preferably 0.98/1 to 1/0.98.

In addition, the liquid crystal polymer may each independently have two or more types of units (1) to (3). In addition, the liquid crystal polymer may have structural units other than units (1) to (3), but the content of other structural units is preferably 10 mol% or less, more preferably 5 mol%, based on the total amount of all units. Ear % below.

In the liquid crystal polymer, the unit (3) having at least one of X and Y as an imine group has at least one of a structural unit derived from an aromatic hydroxylamine and a structural unit derived from an aromatic diamine. Since the solubility in a solvent is excellent, it is preferable, and it is more preferable that only at least one of X and Y is an imine group as a unit (3).

The liquid crystal polymer is preferably produced by melt-polymerizing raw material monomers corresponding to the constituent units constituting the liquid crystal polymer. Melt polymerization can be carried out in the presence of a catalyst. Examples of the catalyst include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide, Nitrogen-containing heterocyclic compounds such as 4-(dimethylamino)pyridine and 1-methylimidazole can be preferably used. In addition, melt polymerization can further be solid-phase polymerization as needed.

The flow initiation temperature of the liquid crystal polymer is preferably 250°C or higher, more preferably 250°C or higher and 350°C or lower, further preferably 260°C or higher and 330°C or lower. When the flow start temperature of the liquid crystal polymer is within the above range, the solubility, heat resistance, strength, and rigidity are excellent, and the viscosity of the solution is moderate.

The flow start temperature is also called the Flow temperature or the flow temperature. It uses a capillary rheometer to increase the temperature at a rate of 4°C/min under a load of 9.8MPa (100kg/cm ² ) and melt the liquid crystal polymer from an inner diameter of 1mm and The temperature at which a viscosity of 4,800 Pa s (48,000 poise) is displayed when extruded through a nozzle with a length of 10 mm is an indicator of the molecular weight of liquid crystal polymers (see Naoyuki Koide, "Liquid Crystal Polymers - Synthesis, Molding, and Applications -" , CMC Corporation, June 5, 1987, p.95).

In addition, the weight average molecular weight of the liquid crystal polymer is preferably at most 1,000,000, more preferably 3,000 to 300,000, still more preferably 5,000 to 100,000, and most preferably 5,000 to 30,000. When the weight average molecular weight of the liquid crystal polymer is within the above range, the thermal conductivity, heat resistance, strength and rigidity of the film after heat treatment in the thickness direction are excellent.

The average thickness of the substrate is not particularly limited, but is preferably from 5 μm to 100 μm, more preferably from 10 μm to 80 μm, and still more preferably from 20 μm to 70 μm.

The average thickness of each layer in the wiring board of the present disclosure is measured using the following method. The wiring board was cut with a microtome, and the cross-section was observed with an optical microscope to evaluate the thickness of each layer. The section sample is cut out at 3 or more places, and the thickness is measured at 3 or more points in each section, and the average value thereof is regarded as the average thickness.

In the wiring board of the present disclosure, from the viewpoint of improving wiring followability and further suppressing wiring deformation, the elastic modulus of the base material at 240° C. is preferably 300 MPa or more, more preferably 400 MPa or more, and even more preferably 450 MPa or more. good. The upper limit of the elastic modulus is not particularly limited, and is, for example, 9000 MPa. Furthermore, the elastic modulus of the substrate at 240° C. was measured by the same method as above.

-Resin layer- It is preferable that a wiring board has a resin layer. The resin layer refers to a layer containing a resin (ie, a polymer). The resin layer may contain components other than resin. Moreover, the resin contained in a resin layer may be only 1 type, and may be 2 or more types. The resin layer may contain resin, or may be a layer in which resin is not a main component. In addition, the main component in a resin layer means the component with the largest content among all the components contained in a resin layer.

Examples of the resin contained in the resin layer include liquid crystal polymers, fluorine-based polymers, polymers of compounds having cyclic aliphatic hydrocarbon groups and ethylenically unsaturated bond groups, polyether ether ketone, poly Olefin, polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfide, polyphenylene ether and its modified substances, polyether imide and other thermoplastic polymers; epoxypropylene methacrylate Elastomers such as copolymers of ester and polyethylene; thermosetting polymers such as phenolic resins, epoxy resins, polyimide resins, and cyanate resins.

Among them, from the viewpoint of dielectric loss tangent, it is preferable that the resin layer contains a thermoplastic polymer, and it is preferable that the thermoplastic polymer is a liquid crystal polymer.

Furthermore, in the present disclosure, a thermoplastic polymer refers to a polymer that softens when heated to its melting point.

The dielectric loss tangent of the resin layer is preferably 0.006 or less, more preferably more than 0 and 0.003 or less.

The content of the resin is preferably at least 10% by mass, more preferably at least 50% by mass, based on the total amount of the resin layer. The upper limit of the resin content is not particularly limited, and may be 100% by mass.

It is more preferable that the resin layer contains a thermoplastic polymer and contains a compound having a melting point lower than that of the thermoplastic polymer (hereinafter also referred to as “compound A”).

In the present disclosure, the melting point is a value calculated from a spectrum obtained by measurement with a differential scanning calorimeter.

The melting point of the thermoplastic polymer is preferably 0°C to 500°C, more preferably 20°C to 400°C.

The melting point of compound A is preferably from 0°C to 240°C, more preferably from 20°C to 190°C.

The difference between the melting point of the thermoplastic polymer and the melting point of Compound A is preferably 10°C to 250°C, more preferably 30°C to 200°C.

From the viewpoint of reducing transmission loss, the dielectric loss tangent of compound A is preferably 0.01 or less, more preferably 0.001 or less.

The dielectric loss tangent of Compound A was measured by the following method.

It was carried out by the resonance perturbation method at a frequency of 28 GHz. Specifically, a split cylinder resonator (manufactured by KANTO Electronic Application and Development Inc.) was connected to a network analyzer (manufactured by Keysight Technologies, Inc. "N5230A"), and PTFE (polytetrafluoroethylene) filled with Compound A was inserted into the cavity resonator. Fluoroethylene) hose (outer diameter 2.5 mm, inner diameter 1.5 mm, length 10 mm), the dielectric loss tangent was measured from the change in resonance frequency before and after insertion and using analysis software manufactured by KANTO Electronic Application and Development Inc. Furthermore, the dielectric loss tangent of the compound A was obtained by correcting the effect of the void in the PTFE tube using Bruggeman's formula and the porosity. The calculation method of the porosity is as follows. Calculate the space volume in the PTFE hose from the inner diameter and length of the PTFE hose. Also, measure the weight before and after filling the solid (powder) in the PTFE hose, and calculate the mass of the filled solid. In addition, the volume of the filled solid is calculated from the mass and specific gravity of the filled solid. The porosity was calculated using the following formula. Porosity (%)=100-(volume of filled solid/space volume in PTFE hose)×100

Compound A may be in the form of particles or fibers. In addition, compound A may be an inorganic compound or an organic compound.

Examples of the material of the inorganic compound include BN, Al ₂ O ₃ , AlN, TiO ₂ , SiO ₂ , barium titanate, strontium titanate, aluminum hydroxide, calcium carbonate, and materials containing two or more of these.

Examples of materials for organic compounds include polyethylene, polystyrene, urea-formalin filler, polyester, cellulose, acrylic resin, fluororesin, hardened epoxy resin, cross-linked benzoguanamine resin, cross-linked Acrylic resins and materials containing two or more of them.

Among them, from the viewpoint of flexibility, it is preferable that compound A is an organic compound, and polyethylene or acrylic resin is more preferable. Also, from the viewpoint of dielectric loss tangent, compound A is preferably an inorganic compound, and boron nitride or silicon dioxide is more preferable.

When Compound A is in the form of particles, the average particle diameter is preferably 0.1 μm to 50 μm, more preferably 1 μm to 20 μm. The average particle size refers to the 50% volume average diameter (D50; also known as the median particle size.).

The content of compound A is preferably 5% by mass to 95% by mass, more preferably 15% by mass to 90% by mass, based on the total amount of the resin layer.

The resin layer may contain resin and other additives other than Compound A. As other additives, known additives can be used. Specifically, for example, a leveling agent, an antifoaming agent, an antioxidant, a ultraviolet absorber, a flame retardant, a coloring agent, etc. are mentioned.

From the viewpoint of improving wiring followability and further suppressing wiring deformation, the elastic modulus of the resin layer at 240° C. is preferably 0.1 MPa or less, more preferably 0.08 MPa or less. The lower limit of the elastic modulus is not particularly limited, and is, for example, 0.0001 MPa.

As a method of providing a resin layer between the wiring patterns and on the wiring patterns, for example, overlapping the resin base material on the wiring pattern of the base material with the wiring pattern and overlapping the base material with the wiring pattern and the resin base material The method of heating in the state. The step of overlapping the resin base material and the process of heating the base material with the wiring pattern and the resin base material are described later.

The method for producing the resin substrate is not particularly limited, and known methods can be referred to. As a manufacturing method of a resin base material, co-casting method, a multilayer coating method, a co-extrusion method etc. are mentioned preferably, for example. Among them, the co-casting method is particularly preferred for relatively thin film production, and the co-extrusion method is particularly preferred for thick film production. In the case of production by the co-casting method and the multi-layer coating method, the composition for layer A formation, the composition for layer B formation, etc., in which the components of each layer such as a polymer are dissolved or dispersed in a solvent, are co-flowed Extended method or multi-layer coating method is preferred.

Examples of solvents include dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, 1-chlorobutane, Halogenated hydrocarbons such as chlorobenzene and o-dichlorobenzene; p-chlorophenol, pentachlorophenol, pentafluorophenol and other halogenated phenols; ethers such as diethyl ether, tetrahydrofuran and 1,4-dichlorobenzene; ketones such as acetone and cyclohexanone; acetic acid Esters such as ethyl ester and γ-butyrolactone; carbonates such as ethylene carbonate and propylene carbonate; amines such as triethylamine; nitrogen-containing heterocyclic aromatic compounds such as pyridine; nitriles such as acetonitrile and succinonitrile; Amides such as dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; urea compounds such as tetramethylurea; nitro compounds such as nitromethane and nitrobenzene; Sulfur compounds such as methylsulfone and cyclobutylene; phosphorus compounds such as hexamethylphosphonamide and tri-n-butylphosphoric acid, etc., and two or more of these may be used.

As a solvent, it is preferable to contain an aprotic compound (particularly preferably an aprotic compound not having a halogen atom) from the viewpoint of low corrosion and easy handling. The proportion of the aprotic compound in the entire solvent is preferably from 50% by mass to 100% by mass, more preferably from 70% by mass to 100% by mass, and most preferably from 90% by mass to 100% by mass. In addition, the above-mentioned aprotic compound includes N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea, N-formaldehyde N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone are more preferred good.

Moreover, as a solvent, it is preferable to contain the compound whose dipole moment is 3-5 from the point which dissolves the said polymer, such as a liquid crystal polymer, easily. The proportion of the compound having a dipole moment of 3 to 5 in the entire solvent is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, most preferably 90% by mass to 100% by mass . As the said aprotic compound, it is preferable to use the compound whose dipole moment is 3-5.

Moreover, as a solvent, it is preferable to contain the compound whose boiling point in 1 atmosphere is 220 degreeC or less from the viewpoint of easy removal. The proportion of the compound having a boiling point of 220° C. or less in 1 atmosphere of the solvent as a whole is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and most preferably 90% by mass to 100% by mass. quality%. As the said aprotic compound, it is preferable to use the compound whose boiling point in 1 atmosphere is 220 degreeC or less.

Moreover, in the manufacturing method of a resin base material, when manufacturing by the above-mentioned co-casting method, a multilayer coating method, a coextrusion method, etc., you may use a support body. As a support body, a metal column, a metal belt, a glass plate, a resin film, or metal foil is mentioned, for example. Among them, the support is preferably metal foil. Examples of resin films include polyimide (PI) films, and examples of commercially available products include UBE INDUSTRIES, LTD. U-Pilex S and U-Pilex R, and DU PONT-TORAY CO., LTD. .Manufactured by Kapton and IF30, IF70 and LV300 manufactured by SKC KOLON PI Company. In addition, a surface treatment layer may be formed on the surface of the support so that it can be easily peeled off. Hard chrome plating, fluororesin, etc. can be used for a surface treatment layer. For example, when the support is a metal foil, a polymer film can be formed by applying a polymer solution containing a polymer on the metal foil and drying it. A resin substrate can be obtained by etching and removing the metal foil on which the polymer film is formed.

The average thickness of the support is not particularly limited, but is preferably not less than 25 μm and not more than 75 μm, more preferably not less than 50 μm and not more than 75 μm.

Also, there is no particular limitation on the method of removing at least a part of the solvent from the cast or coated film-like composition (cast film or coating film), and a known drying method can be used.

A polymer film was obtained by the above film formation.

In the production method of the resin base material, stretching of the polymer film may be performed from the viewpoint of controlling the molecular alignment and adjusting the coefficient of linear expansion and mechanical properties. The stretching method is not particularly limited, and known methods can be referred to, and it can be carried out in a state containing a solvent, or in a state of a dry film. Stretching in a solvent-containing state may be carried out while holding the resin substrate, or may be performed without stretching by utilizing the self-shrinking force of a dried web, or may be a combination of these. In the case of reducing the brittleness of the resin substrate by adding an inorganic filler or the like, stretching is particularly effective for the purpose of improving the elongation at break and the strength at break.

It is preferable that the manufacturing method of the resin substrate includes the step of heat-treating (annealing) the polymer film. Specifically, the heat treatment temperature in the step of performing the above heat treatment is preferably 260°C to 370°C, more preferably 280°C to 360°C, and 300°C to 350°C from the viewpoint of dielectric loss tangent and peel strength. for further improvement. The heat treatment time is preferably 15 minutes to 10 hours, more preferably 30 minutes to 5 hours. Moreover, the manufacturing method of a resin base material may also include other well-known steps as needed.

<Manufacturing method of wiring board> The manufacturing method of the wiring board of the present disclosure includes a step of overlaying a resin base material on a wiring pattern of a wiring pattern base material (hereinafter, an overlapping step) and heating in a state where the wiring pattern base material and the resin base material are polymerized. Step to obtain a wiring board (hereinafter, heating step). Among the substrates with wiring patterns, the modulus of elasticity at the heating temperature when the substrates are heated in a stacked state is 300 MPa or more, and the dielectric loss tangent of the wiring board is 0.006 or less.

-overlapping steps- In the manufacturing method of the wiring board of this disclosure, the resin base material is overlapped on the wiring pattern of the wiring pattern base material. Before embedding the wiring pattern in the heating step described later, the resin base material is placed on the wiring pattern in advance.

In the case of overlapping the resin base material, the resin base material may be placed only on the wiring pattern, or the resin base material may be pressed and bonded to the wiring pattern by applying pressure.

In the base material with a wiring pattern, the wiring pattern may be formed on only one surface of the base material, or the wiring pattern may be formed on both surfaces of the base material.

The base material with a wiring pattern can be produced using a well-known method. For example, a metal layer is attached to at least one surface of the base material to obtain a laminate including the base material and the metal layer disposed on at least one surface of the base material. A well-known patterning treatment is performed on the metal layer, thereby obtaining a substrate with a wiring pattern.

Preferred aspects of the base material and the wiring pattern in the base material with a wiring pattern are the same as the preferred aspects of the base material and the wiring pattern described in the section of the above-mentioned wiring board. A preferred aspect of the resin base material is the same as the preferred aspect of the resin layer described in the section of the above-mentioned wiring board except for the points described below.

The resin base material is manufactured, for example, by the manufacturing method of the resin base material used when providing the resin layer demonstrated in the said wiring board column.

Among the substrates with wiring patterns, the modulus of elasticity at the heating temperature when the substrate is heated in an overlapping state in the heating step described later is preferably 300 MPa or more, more preferably 350 MPa or more, and even more preferably 400 MPa or more. good. The upper limit of the elastic modulus is not particularly limited, and is, for example, 9000 MPa. The measuring method of the modulus of elasticity is as described above.

The modulus of elasticity at the heating temperature when the resin substrates are heated in a stacked state in the heating step described later is preferably 0.1 MPa or less, more preferably 0.08 MPa or less. The lower limit of the elastic modulus is not particularly limited, and is, for example, 0.0001 MPa. The measuring method of the modulus of elasticity is as described above. The resin base material preferably contains a thermoplastic polymer.

It is preferable that the resin base further contains a compound having a melting point lower than that of the thermoplastic polymer (that is, compound A).

-Heating step- In the method of manufacturing a wiring board according to the present disclosure, after the above-mentioned overlaying step, heating is performed in a state in which the base material with wiring patterns and the resin base material are overlaid to obtain a wiring board. In the obtained wiring board, a wiring pattern may be buried between the base material and the resin base material.

The heating method is not particularly limited, and can be performed, for example, using a heat press.

The heating temperature when heating the base material with the wiring pattern and the resin base material in a state where they are overlapped is preferably 50°C to 300°C, more preferably 100°C to 250°C. From the standpoint of improving wiring followability and further suppressing wiring deformation, the above-mentioned heating temperature is preferably a temperature lower than the melting point of the thermoplastic polymer contained in the resin base material, and a temperature lower than the melting point of the thermoplastic polymer by more than 10°C is better. The measuring method of the melting point is as described above.

Also, when the resin base material further contains compound A having a melting point lower than that of the thermoplastic polymer, the above-mentioned heating temperature is higher than the melting point of compound A from the viewpoint of improving wiring followability and further suppressing wiring deformation. The temperature is preferable, and the temperature higher than the melting point of Compound A by 10° C. or more is more preferable.

It is preferable to pressurize when heating in the state which overlapped the base material with a wiring pattern and a resin base material. The pressure is preferably 0.5MPa-30MPa, more preferably 1MPa-20MPa.

The heating time at the time of heating in the state which overlapped the base material with a wiring pattern and a resin base material is not specifically limited, For example, it is 1 minute - 2 hours.

＜Use＞ The wiring board of this disclosure can be used for various purposes. Among them, the wiring substrate of the present disclosure can be preferably used for a flexible printed circuit substrate. [Example]

Examples are given below to describe the present disclosure in further detail. Materials, usage amounts, ratios, processing contents, processing procedures, etc. shown in the following examples can be appropriately changed unless departing from the gist of the present disclosure. Therefore, the scope of the present disclosure is not limited to the specific examples shown below.

Details of materials used in Examples and Comparative Examples are as follows.

(substrate) • Liquid crystal polymer... Liquid crystal polymer film (product name "VECSTAR CTQ-50", film thickness 50 μm, manufactured by Kuraray Co., Ltd.) •Polyimide...polyimide film (product name "UPILEX 50S", film thickness 50μm, manufactured by UBE INDUSTRIES, LTD.) •Fluororesin...copolymer film of 4-fluoroethylene and 6-fluoropropylene (product name "NR0538-02", film thickness 50μm, manufactured by DAIKIN INDUSTRIES, LTD) • PET...Polyethylene terephthalate film (product name "lumirror #50-S10", film thickness 50 μm, manufactured by TORAY INDUSTRIES, INC.)

(resin layer) -polymer- •LCP...a liquid crystal polymer prepared according to the following manufacturing method

-Manufacture of LCP- Add 940.9 g (5.0 moles) of 6-hydroxy-2-naphthoic acid, 377.9 g (2.5 moles) of acetaminophen to the reactor equipped with stirring device, torque meter, nitrogen inlet pipe, thermometer and reflux cooler ), 415.3g (2.5 moles) of isophthalic acid and 867.8g (8.4 moles) of acetic anhydride. After replacing the gas in the reactor with nitrogen, stir under nitrogen flow and change from room temperature (23°C to ) to 143°C and reflux at 143°C for 1 hour. Next, after distilling by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150° C. to 300° C. over 5 hours and kept at 300° C. for 30 minutes, and then the contents were taken out from the reactor and cooled to room temperature. The obtained solid matter was pulverized with a pulverizer to obtain a powdery liquid crystal polyester (A1).

For the liquid crystal polyester (A1) obtained above, the temperature was raised from room temperature to 160°C in nitrogen atmosphere over 2 hours and 20 minutes, then from 160°C to 180°C over 3 hours and 20 minutes, and kept at 180°C for 5 Hours, thereby cooling after solid-state polymerization, followed by pulverization with a pulverizer, to obtain a powdery liquid crystal polyester (A2).

For the liquid crystal polyester (A2) obtained above, the temperature was raised from room temperature (23°C) to 180°C in a nitrogen atmosphere for 1 hour and 20 minutes, and then from 180°C to 240°C over 5 hours. Cooling was carried out after the solid-state polymerization by holding for 5 hours, and a powdery liquid crystal polyester (LCP) was obtained.

-Additive: Compound A- • CL-2080... Spherical low-density polyethylene (product name "Flowing Beads CL-2080", median particle size 11μm, melting point 105°C, density 0.92g/cm ³ , dielectric loss tangent 0.0007, manufactured by Sumitomo Seika Chemicals Company, Ltd.)

-filler- F-1: Silica microparticles with an average particle diameter of 0.5 μm (product name “SO-C2”, manufactured by Admatechs Co., Ltd.) F-2: Boron nitride particles (product name "HP40MF100", manufactured by MIZUSHIMA FERROALLOY CO., LTD., dielectric loss tangent 0.0007)

<Example 1> -Manufacturing of base material with wiring pattern- Copper foil (product name "CF-T4X-SV-18", average thickness 18 μm, manufactured by FUKUDA METAL FOIL & POWDER CO., LTD.) and a liquid crystal polymer film (product name "CTQ-50" , average thickness 50 μm, manufactured by Kuraray Co., Ltd.). The copper foil, the base material, and the copper foil were sequentially stacked so that the treated surface of the copper foil came into contact with the base material. Using a laminator (product name "Vacuum Laminator V-130", manufactured by Nikko-Materials Co., Ltd.), lamination was performed at 140°C and a lamination pressure of 0.4 MPa for 1 minute to obtain Precursor for double-sided copper-clad laminates. Next, the precursor of the obtained double-sided copper-clad laminate was heated at 300°C and 4.5 MPa using a thermocompression bonding machine (product name "MP-SNL", manufactured by Toyo Seiki Seisaku-sho, Ltd.). Crimping was carried out for 10 minutes, thereby producing a double-sided copper-clad laminate. The copper foils on both sides of the above-mentioned double-sided copper-clad laminate were respectively etched and patterned, and a substrate with wiring patterns including ground lines and 3 pairs of signal lines was produced on both sides of the substrate. The length of the signal line is set to 50mm, and the width is set so that the characteristic impedance becomes 50Ω.

-Manufacturing of wiring boards- After heating 0.36 g of LCP and 4.19 g of N-methylpyrrolidone at 90° C. for 4 hours, it was left to cool to room temperature. 1.45 g of CL-2080 and 4 g of N-methylpyrrolidone (manufactured by FUJIFILM Wako Pure Chemical Corporation) were added and stirred well to obtain a polymer solution. After coating the polymer solution on copper foil (product name "CF-T9DA-SV-18", average thickness 18 μm, manufactured by FUKUDA METAL FOIL & POWDER CO., LTD.) using an applicator (gap: 250 μm) , dried at 50°C for 3 hours to obtain a polymer film. The application and drying of the polymer solution were repeated twice to form a polymer film with a film thickness of 25 μm. After performing preliminary drying at 120° C. for 1 hour, annealing treatment was performed at 280° C. for 3 hours in a nitrogen atmosphere. Thereby, a laminate in which a polymer film was formed on a copper foil was obtained. The laminate was immersed in an aqueous solution of iron (III) chloride (solid content: 40% by mass, manufactured by FUJIFILM Wako Pure Chemical Corporation) for 1 hour, and the copper foil was removed by etching, followed by washing with water. Thereby, a polymer film (resin substrate) was obtained. The polymer film, the substrate with wiring pattern and the polymer film are sequentially laminated in such a way that the polymer film is opposed to the wiring pattern side of the substrate with wiring pattern (overlapping step) at 160°C and 4MPa Heat pressing (heating step) for 1 hour, whereby a wiring board having the same structure as in FIG. 2 was obtained. Wiring patterns (ground lines and signal lines) were embedded in the obtained wiring substrate, and the thickness of the wiring patterns was 18 μm.

<Example 2, Comparative Example 1, Comparative Example 2> In Example 2 and Comparative Example 1, the wiring was obtained by the same method as in Example 1 except that the base material was changed to the base material described in Table 1 in the preparation of the base material with wiring pattern. substrate. In Comparative Example 2, in making the base material with the wiring pattern, the base material was changed to the base material described in Table 1, and the temperature of the hot pressing was changed to 200°C. 1 The wiring board was obtained in the same way.

<Example 3> In producing the base material with wiring pattern of Example 1, it implemented similarly to Example 1 except having changed the double-sided copper-clad laminated board into the following double-sided copper-clad laminated board.

-Manufacturing of single-sided copper-clad laminates- After heating 0.91 g of LCP and 10.47 g of N-methylpyrrolidone at 90° C. for 4 hours, it was left to cool to room temperature. 0.90 g of F-1 and 4 g of N-methylpyrrolidone (manufactured by FUJIFILM Wako Pure Chemical Corporation) were added and stirred well to obtain a polymer solution. After coating the polymer solution on a copper foil (product name "CF-T4X-SV-18", average thickness 18 μm, manufactured by FUKUDA METAL FOIL & POWDER CO., LTD.) using an applicator (gap: 250 μm) , dried at 50°C for 3 hours to obtain a polymer film. After performing preliminary drying at 120° C. for 1 hour, annealing treatment was performed at 280° C. for 3 hours in a nitrogen atmosphere. Thereby, a single-sided copper-clad laminate in which a polymer film was formed on a copper foil was obtained.

-Manufacturing of double-sided copper-clad laminates- (Copper Clad Laminate Precursor Step) Using a laminator (“Vacuum Laminator V-130” manufactured by Nikko-Materials Co., Ltd.), laminate single-sided copper-clad laminates at 140°C and a lamination pressure of 0.4MPa for 1 minute Processed and placed so that the treated surface of copper foil (manufactured by FUKUDA METAL FOIL & POWDER CO., LTD., CF-T4X-SV-18, with an average thickness of 18 μm) is in contact with the polymer film to obtain a precursor of a double-sided copper foil laminate things.

(this thermocompression step) Using a thermocompression bonding machine ("MP-SNL" manufactured by Toyo Seiki Seisaku-sho, Ltd.), the obtained copper-clad laminate precursor was thermocompressed at 300°C and 4.5MPa for 10 minutes to produce Copper-clad laminates on both sides.

<Example 4> In producing the single-sided copper-clad laminated board of Example 3, it implemented similarly to Example 3 except having changed 0.90g of F-1 into 0.90g of F-2.

Using the obtained wiring board, the dielectric loss tangent and elastic modulus were measured. Specifically, regarding the elastic modulus, the elastic modulus at 240° C. and heating temperature in the thickness region P21, the elastic modulus at 240° C. and the heating temperature in the thickness region P22, and the 240° C. and heating temperature of the resin layer 60 were measured. The modulus of elasticity below. In addition, the heating temperature means the temperature at the time of heating in the state which overlapped the base material with the wiring pattern and the resin base material, and corresponds to the temperature of the said hot-pressing. The thickness region P21 refers to a thickness region to a thickness position of 7 μm in a direction away from the wiring pattern based on the surface on the resin layer side in the thickness direction of the wiring pattern 50 . The thickness region P22 refers to a thickness region up to a thickness position of 7 μm in a direction away from the wiring pattern based on the surface on the base material side in the thickness direction of the wiring pattern 50 . In addition, the thickness region P21 is replaced with a thickness region until a thickness position corresponding to 40% of the thickness of the wiring pattern is oriented in a direction away from the wiring pattern on the basis of the surface on the resin layer side in the thickness direction of the wiring pattern 50 In this case, the measurement results described later may be the same. In addition, the thickness region P22 is replaced with a thickness region corresponding to a thickness position corresponding to 40% of the thickness of the wiring pattern in the direction away from the wiring pattern based on the surface on the substrate side in the thickness direction of the wiring pattern 50. In other cases, the measurement results described later may be the same.

-Measurement- [Dielectric loss tangent] It was carried out by the resonance perturbation method at a frequency of 28 GHz. Specifically, a split cylinder resonator (manufactured by KANTO Electronic Application and Development Inc.) was connected to a network analyzer (manufactured by Keysight Technologies "N5230A"), and a test piece (width: 25mm x length: 50mm, 24°C. 50% • 24-hour humidity control) was inserted into the cavity resonator, and the dielectric loss tangent was measured from the change of the resonance frequency before and after the insertion and using an analysis software made by KANTO Electronic Application and Development Inc.

[elastic modulus] First, cut the cross-section of the wiring board with a microtome, observe the image near the wiring with an optical microscope, and identify the side that is far away from the wiring pattern based on each of the one surface and the other surface in the thickness direction of the wiring pattern. Direction to the thickness region of the thickness position of 7 μm. Next, using the nanoindentation method, the elastic modulus in the above-mentioned specific region was measured as the indentation elastic modulus. The indentation modulus of elasticity is measured, for example, by applying a microhardness tester (product name "DUH-W201", manufactured by Shimadzu Corporation) to the above-mentioned specific region with a Vickers indenter at a load speed of 0.28 mN/sec. The load was kept at a maximum load of 10 mN for 10 seconds, and then unloaded at a load speed of 0.28 mN/sec.

-Evaluation- [wiring follow-up characteristics] The wiring board was sliced in the thickness direction with a microtome, and the cross-section of resin layer 60/wiring pattern 50/substrate 40/wiring pattern 70/resin layer 80 laminated in this order was observed with an optical microscope. Between the resin layer 60 and the wiring pattern 50, the length L of the gap generated in the in-plane direction of the above cross-section was measured. The average value among 10 sites was calculated. The evaluation criteria are as follows. A: L is 0 μm. B: L exceeds 0 μm and is 4 μm or less. C: L exceeds 4 μm and is 20 μm or less. D: L exceeds 20 μm.

[wiring deformation] The wiring board was cut with a microtome, and the cross section was observed with an optical microscope. Wiring deformation was evaluated based on the presence or absence of deformation in signal lines and ground lines. The evaluation criteria are as follows. A: No deformation was observed in the signal wire and the ground wire. B: No deformation was observed in the signal wire, but deformation was observed in the ground wire. C: Deformation was observed in 1 pair of signal lines. D: Deformation is observed in 2-pair or 3-pair signal lines.

Table 1 shows the measurement results and evaluation results.

[Table 1] Substrate with wiring pattern resin layer Wiring board Heating temperature [°C] Evaluation Substrate Wiring thickness [μm] Dielectric loss tangent Elastic modulus [MPa] Elastic modulus [MPa] Dielectric loss tangent Wiring followability Wiring deformation type Dielectric loss tangent Film thickness [μm] 240°C heating temperature Thickness area P21 Thickness area P22 240°C heating temperature 240°C heating temperature Example 1 LCP 0.002 50 18 0.002 0.01 0.04 3 70 400 1000 0.0020 160 A A Example 2 polyimide 0.011 50 18 0.002 0.01 0.04 3 70 1200 1800 0.006 160 A A Example 3 LCP/F-1 0.003 50 18 0.002 0.01 0.04 3 70 450 1100 0.003 160 A A Example 4 LCP/F-2 0.003 50 18 0.002 0.01 0.04 3 70 500 1150 0.003 160 A A Comparative example 1 Fluorine resin 0.0002 50 18 0.002 0.01 0.04 3 70 40 100 0.0008 160 A D. Comparative example 2 PET 0.003 50 18 0.002 0.01 0.02 3 6 80 250 0.003 200 A D.

As shown in Table 1, in Examples 1 to 4, it can be seen that the buried wiring pattern is based on each of the one surface and the other surface in the thickness direction of the wiring pattern, and the thickness up to a specific thickness position At least one of the regions has an elastic modulus at 240° C. of 300 MPa or more and a dielectric loss tangent of 0.006 or less. Therefore, wiring deformation is excellent and wiring deformation is suppressed.

On the other hand, in Comparative Example 1 and Comparative Example 2, it can be seen that the thickness region up to a specific thickness position is at 240° C. based on each of the one surface and the other surface in the thickness direction of the wiring pattern. Since the modulus of elasticity was less than 300 MPa, it was not possible to achieve both wiring followability and suppression of wiring deformation.

100,200: wiring board 10,40: Substrate 20, 50, 70: wiring pattern 30,60,80: resin layer P11, P12, P21, P22, P31, P32: thickness area

FIG. 1 is a schematic cross-sectional view showing an example of a wiring board of the present disclosure. FIG. 2 is a schematic cross-sectional view showing another example of the wiring board of the present disclosure.

100: wiring board

10: Substrate

20: Wiring pattern

30: resin layer

P11, P12: thickness area

Claims (12)

A wiring board in which a wiring pattern is buried, Elastic modulus at 240°C of at least one of the thickness regions facing away from the wiring pattern to a thickness position of 7 μm, based on each of the one surface and the other surface in the thickness direction of the wiring pattern is above 300MPa, The dielectric loss tangent is 0.006 or less. A wiring board in which a wiring pattern is buried, At least one of the thickness regions facing away from the wiring pattern to a thickness position corresponding to 40% of the thickness of the wiring pattern based on each of one surface and the other surface in the thickness direction of the wiring pattern The modulus of elasticity at 240°C is above 300MPa, The dielectric loss tangent is 0.006 or less. The wiring substrate as described in claim 1 or claim 2, wherein The aforementioned wiring pattern has a thickness of 5 μm to 40 μm. The wiring board according to claim 1 or claim 2, comprising a base material, the wiring pattern disposed on at least one surface of the base material, and a resin layer disposed between the wiring patterns and on the wiring pattern , The dielectric loss tangent of the base material is 0.006 or less. The wiring substrate as described in Claim 4, wherein The aforementioned base material contains a liquid crystal polymer. The wiring board according to claim 5, wherein the liquid crystal polymer has a constituent unit represented by any one of formula (1) to formula (3), formula (1) -O-Ar ¹ -CO- formula (2 )-CO-Ar ² -CO- Formula (3) -X-Ar ³ -Y- In formula (1) ~ formula (3), Ar ¹ represents phenylene, naphthylene or biphenylene, Ar ² and Ar ³ each independently represent a phenylene group, a naphthylene group, a biphenylene group or a group represented by the following formula (4), X and Y each independently represent an oxygen atom or an imine group, and Ar ¹ to Ar At least one of the hydrogen atoms in ³ can be independently replaced by a halogen atom, an alkyl group or an aryl group, formula (4)-Ar ⁴ -Z-Ar ⁵ - In formula (4), Ar ⁴ and Ar ⁵ are independently Represents phenylene or naphthyl, and Z represents oxygen atom, sulfur atom, carbonyl, sulfonyl or alkylene. The wiring substrate as described in Claim 5, wherein The elastic modulus at 240° C. of the aforementioned resin layer is 0.1 MPa or less. A method of manufacturing a wiring board, comprising: A step of overlapping the resin base material on the wiring pattern of the wiring pattern-attached base material; and A step of obtaining a wiring board by heating the base material with the wiring pattern and the resin base material in a state where they are overlapped, The modulus of elasticity of the base material at the heating temperature when the base material is heated in the overlapping state is 300 MPa or more, among the base materials with wiring patterns, The dielectric loss tangent of the above-mentioned wiring board is 0.006 or less. The method of manufacturing a wiring board according to claim 8, wherein The aforementioned resin base material contains a thermoplastic polymer, The heating temperature at the time of heating in the overlapping state is lower than the melting point of the thermoplastic polymer. The method of manufacturing a wiring board according to Claim 9, wherein The aforementioned resin base material further contains a compound having a melting point lower than that of the aforementioned thermoplastic polymer, The heating temperature at the time of heating in the overlapping state is higher than the melting point of the aforementioned compound. The method of manufacturing a wiring board according to Claim 10, wherein The dielectric loss tangent of the aforementioned compound is 0.01 or less. The method of manufacturing a wiring board according to any one of claim 8 to claim 11, wherein The modulus of elasticity at the heating temperature when the resin base material is heated in the stacked state is 0.1 MPa or less.

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